twins

[silverdmax]

how much boost can a stock lbz block take. i just was trying to find out.

[ripmf666]

As in with stock head bolts and nothing else. I made 40+ with no trouble with a single.

[Nick]

Short answer: It depends on the tuning.

45-50 is no problem with conservative tuning.

Nick

[silverdmax]

thanks okay thats what i thought. think i will just settle with my stock turbo until i can afford head studs. i really just want a moded stock turbo like danville, fleece or even a garrett 4094vvt would be sweet.
:thumb:

[ripmf666]

Really most will crack a piston before lifting a head on a LBZ motor so with the right tuning like Nick said you will be fine.

[Tyler@MPF]

With my 4094vvt, it is tuned to about 34-35 psi. So if you decide a single you won't push the limits of the stock head bolts.

[OTHRGRL]

Really most will crack a piston before lifting a head on a LBZ motor so with the right tuning like Nick said you will be fine.

I agree. Other than the fluke cases of blown head gaskets at low power numbers, on the Duramax you will typically run into other problems at about the same time as head gaskets when you push them too far. On LB7-LLY I have seen bent rods, one of which broke and went through the block without ever lifting a stock head. I have also seen destroyed pistons without lifting a head on an LLY. On LBZs it's typically the pistons. If you need head studs than you most likely need pistons and rods at the same time.

[silverdmax]

want to hit close to 500hp and be able to tow without seeing crazy egts. im just looking for some ideas. do i need a lift pump to reach that amount of horsepower.

[Dmax15]

If I were you I would go with a lift pump at that power level, it will take some stress off the CP3.

As far as twins go and head gasket failures, they seem to be the way to go as far as longevity and keeping EGT's down with some added power.

And for an aftermarket turbo I would give Dustin a call, I've heard he can set you up with a nice turbo setup and tuning to go with it:thumb:

[silverdmax]

im holding off on twins right now but i am looking to get a lift pump soon.

[OTHRGRL]

want to hit close to 500hp and be able to tow without seeing crazy egts. im just looking for some ideas. do i need a lift pump to reach that amount of horsepower.

To reach a reliable 500 rwhp on an LBZ you need an exhaust, built trans with a good converter, and tuning. That's it.

As DMax15 said though, the lift pump will take stress off the CP3 and help it last longer. That and shimming the FPRV will also get you up to about 540 rwhp.

To help with EGTs and add power without stressing the motor any more (no added fuel or boost) you can do more air flow upgrades. An S&B intake, the AFE or Banks driver's side 3" boost tube, Pro-Fab manifolds and up-pipes, Pro-Fab down pipe, and the Pro-Fab EGR delete tube will all help smooth the airflow into and out of the motor - freeing up some horsepower that was being lost to restrictions in the system. The right tuning with those airflow upgrades and a stock turbo should easily be over 575 rwhp with very managable EGTs while towing.

If you want more a turbo or twins can get you up to about 600 before you are about out of fuel from a single stock CP3.

[silverdmax]

i have an exhaust 4inch turbo back,bd manifold for more flow but i didnt think would i need a cai because how well the stock filter flows air. as for a tranny i have a bd torque converter and a transgo jr. what kind of tranny modds would i be needing to hold 500hp.

[OTHRGRL]

BD has single and triple disc converters. The single is rated by them for 900 ft lbs of torque, most likely refering to crank output numbers. With a 500 rwhp tune you will be at or above 900 ft lbs at the wheels and even higher at the crank. If you have a triple disc it should hold it fine but the only experience I have with BD converters is taking them out to install SunCoast or Precision Industries converters in their place during builds. To hold 500 rwhp I would recommend at least a SunCoast Stage III or equivalent transmission build. With your setup your C3 clutches will be your next weak link and it won't take much 500 hp abuse to start slipping them and going into limp mode.

We have made 590 rwhp through a stock LBZ intake on an LLY with a stock turbo and dual fuelers - so you are right that your stock intake will flow plenty for 500hp, but when you go over that a good CAI will help.

[mikeholmen]

Twins are the only way to really make power. Anything over 45-50psi, the turbocharger is out of its ablity to compressor effiency. The compressor is pushed into overspeed, snap break goes the shaft.

I want to run the stock turbo with an upgraded hi-flow GT40 wheel over a GT5541R, using two external gate to bypass the secondary turbo. Done a few cummins this way, works well.

[OTHRGRL]

Twins are the only way to really make power.

Really??? 5 out of the top 6 competitors in last year's Diesel Power Challenge were running single turbos, and one of them was an '08 Power Stroke that came with compounds from the factory and ditched them for a single turbo.

Anything over 32-34 PSI of boost pressure out of a factory turbo is out of it's map and hurting your power. On an LLY we've done 604 rwhp on the stock turbo with only 32-34 PSI of boost on fuel only.

"Twins" or compounds will get you less power than what the big charger would be capable of on it's own - the added stage reduces overall effeciency. The reason for compounding is to have the streetability of the small charger with most of the top end performance of the big charger. Before getting to 800+ rwhp on a single turbo meant an S475 or GT4202 and for many that was too big or laggy for their liking or for their towing needs. So a more streetable way to get there was an S366/S480 compound setup (see how you need an 80mm big turbo to get the power of a single 74mm). The great thing for us is that turbo manufacturers have been really pushing the envelope these days to get more power out of their turbos. Now a single BatMoWheel S366 will do up to 850 rwhp on fuel only and because of it's lighter compressor spools faster than the S366's that are commonly used in compound setups. Even in the biggest, "least streetable" (but highest power potential) setup the BatMo S366 spools up about like a stock LB7 charger, but instead of leveling out at 30-32 PSI it just keeps pushing you back in the seat and peaks out at 45-50 PSI, even on a stock fueling system with a lift pump.

If 850 rwhp isn't going to be enough step up to a BatMo S475, we have a handful of local trucks that are daily drivers used for towing with that turbo and they all love them; most of them are stock motors and stock fueling systems. With a little transmission tuning that turbo spools very easily and can be daily driven and used to tow - pushed to it's max it is capable of 950+ rwhp.

[mikeholmen]

Yes and no, twins work done lots. Had a few truck over 1000rwhp. Had a few truck near 1000rwhp on singles, not saying it can't be done. For a street daily truck that used as a truck, twins are the only way. Yes, typically to many guys put in way to big of secondary. We have good success running the GT35/S478LI in twins, with a few extra tweaks. Spool wicked fast to 60psi, intial spool is slightly slower (I think that caused by a boost leak), but once its spool its a strong hard pull till you lift the throttle.

[OTHRGRL]

I'm not saying twins don't work - I have installed them and tune a number of trucks with them. I'm saying that in most cases the correct single will do everything people need it to. The biggest selling point people make for twins is having the streetablity of the small charger but with more top end power - mugh like you are trying to say with this statement.

For a street daily truck that used as a truck, twins are the only way.

In my opinion that is completely false. You can get 850 rwhp out of a truck with a single that is perfectly streetable, daily driven, and able to be used as a truck. Like I said a BatMo S366 will do all of those things - that is what is going on my daily driver, street truck, that will be used to tow the race truck and customers' trucks to and from the shop. I have a number of customers with billet and BatMo S475s that daily drive their trucks, tow with them, and love the way they drive and tow - and that charger is capable of 950+ rwhp.

The smallest turbo upgrade I recommend on a Duramax is an S366 for someone that needs to be able to tow extremely heavy and have a turbo that spools instantly - I have one customer that has weighed in at 36,000+ lbs that has one and it tows just fine for him. It spools "wicked fast" and with enough fueling will push over 50 PSI. If you still need that kind of streetability and 850 rwhp isn't enough for you then I could see compounding an S480 or S483 with it like we are doing on an LMM (BatMo 366 - BatMo 483). For anyone that doesn't primarily tow with their truck and/or only tows up to 15,000 lbs an S475 will work fine. With some small TCM adjustments it spools very nicely and with enough fuel will push over 60 PSI.

On my personal truck I was running a cast wheel S480 as a single and was still able to tow another Duramax on a trailer, a BatMo S480 would have been even better towing and is capable of 1000+ rwhp.

So twins are certainly not "the only way to really make power" and are also not "the only way for a street daily truck that used as a truck" - there are other options that are just as capable for both power and towing and at a much lower cost with less parts to fail and clutter under the hood. Do compounds still have a place in diesel performance - of course, they are just not the end all, be all modification that many make them out to be.

On a Cummins, like you are used to, that has a harder time spooling a decent sized charger they make more sense. I find it funny that everyone that makes twin kits (as you do) trys to spread propaganda that all single turbos that make good power are not streetable and that you "have to have twins if you want to be able to still daily drive and use your truck"; while places like myself that sell both single turbo kits and twin turbo kits will give you real world experience from both and let you decide. I would opbviously make more selling a twin kit and 2 turbos instead of one, but I am all about being honest with my customers and helping them get the best bang for their buck.

[crazycrew]

WOW! Thanks for that explanation Dustin. I certainly learned a thing or 2 in this thread:thumb:

[quentomania]

That's some good info! Mine and many others see 60 pounds on a stock LBZ with twins.

[mikeholmen]

I'm not saying twins don't work - I have installed them and tune a number of trucks with them. I'm saying that in most cases the correct single will do everything people need it to. The biggest selling point people make for twins is having the streetablity of the small charger but with more top end power - mugh like you are trying to say with this statement.



In my opinion that is completely false. You can get 850 rwhp out of a truck with a single that is perfectly streetable, daily driven, and able to be used as a truck. Like I said a BatMo S366 will do all of those things - that is what is going on my daily driver, street truck, that will be used to tow the race truck and customers' trucks to and from the shop. I have a number of customers with billet and BatMo S475s that daily drive their trucks, tow with them, and love the way they drive and tow - and that charger is capable of 950+ rwhp.

The smallest turbo upgrade I recommend on a Duramax is an S366 for someone that needs to be able to tow extremely heavy and have a turbo that spools instantly - I have one customer that has weighed in at 36,000+ lbs that has one and it tows just fine for him. It spools "wicked fast" and with enough fueling will push over 50 PSI. If you still need that kind of streetability and 850 rwhp isn't enough for you then I could see compounding an S480 or S483 with it like we are doing on an LMM (BatMo 366 - BatMo 483). For anyone that doesn't primarily tow with their truck and/or only tows up to 15,000 lbs an S475 will work fine. With some small TCM adjustments it spools very nicely and with enough fuel will push over 60 PSI.

On my personal truck I was running a cast wheel S480 as a single and was still able to tow another Duramax on a trailer, a BatMo S480 would have been even better towing and is capable of 1000+ rwhp.

So twins are certainly not "the only way to really make power" and are also not "the only way for a street daily truck that used as a truck" - there are other options that are just as capable for both power and towing and at a much lower cost with less parts to fail and clutter under the hood. Do compounds still have a place in diesel performance - of course, they are just not the end all, be all modification that many make them out to be.

On a Cummins, like you are used to, that has a harder time spooling a decent sized charger they make more sense. I find it funny that everyone that makes twin kits (as you do) trys to spread propaganda that all single turbos that make good power are not streetable and that you "have to have twins if you want to be able to still daily drive and use your truck"; while places like myself that sell both single turbo kits and twin turbo kits will give you real world experience from both and let you decide. I would opbviously make more selling a twin kit and 2 turbos instead of one, but I am all about being honest with my customers and helping them get the best bang for their buck.

What converter you using? What elevation you at? The S366 are slugs. Tried lots of different ones. T3/T4 with different turbine wheel and turbine A/R housings. Also how long does a S366 last at 80psi? Seen lots of them broken, but then again they only cost around $500, so yes they are cheap.

80psi, please run an external gate or open the wastegate. That turbo is way way out off the compressor map. Most have at most a 5:1 pressure ratio for maps.

Done lots of twins and ran lots of big singles. Ya even a S475 with spool, with the right set-up. Just are smokey beasts for a daily drivers.

[OTHRGRL]

What converter you using? What elevation you at? The S366 are slugs. Tried lots of different ones. T3/T4 with different turbine wheel and turbine A/R housings. Also how long does a S366 last at 80psi? Seen lots of them broken, but then again they only cost around $500, so yes they are cheap.

80psi, please run an external gate or open the wastegate. That turbo is way way out off the compressor map. Most have at most a 5:1 pressure ratio for maps.

Done lots of twins and ran lots of big singles. Ya even a S475 with spool, with the right set-up. Just are smokey beasts for a daily drivers.

Mike,

First we are talking about Duramax's here - 6.6L V8s that have heads that flow and like to rev; not 5.9L I6s that rev slower and have piss poor flow in the heads. Then there's the custom tuning capability of EFI Live. Second I re-read my post and don't see 80 PSI mentioned anywhere in it.

We use Precision Industries converters, with up to an S366 the ML series works just fine; with S400s the DA series works great. I am at sea level myself but have customers that live and/or tow through the mountains and have personally towed a trailer with another Duramax and tools, tires and spare parts through the mountains of Western NC, Eastern TN, and into Kentucky - all with an S475 single on a stock LBZ. I towed that LBZ back to it's owner behind my truck with an S480 single.

Maybe the fact that you are buying $500 S366's has something to do with your lack of success with them. I haven't had problems with the S366s that I get from BullsEye Power.

I have quite a few customers with S475s as singles that don't smoke unless they want them to and they spool up and tow just fine. A Billet or BatMo S366 spools about like a stock LB7 charger - just sent one home Friday and have 2 more here at the shop right now.